printf count utf-8 chars like arrow wrong

The printf command in bash (builtin) and corutils /usb/bin/printf have an error in counting the length of a string, if a non-ascii character is involved.
Example is the arrow - type Alt+I.

Try the following commands:
printf -v r "%-2s X\n" '→' ; echo ${#r} # prints 4
printf -v r "%-2s X\n" ' ' ; echo ${#r} # prints 5

The coreutils version of printf has the same misbehaviour.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: coreutils 8.25-2ubuntu3~16.04
ProcVersionSignature: Ubuntu 4.10.0-32.36~16.04.1-generic 4.10.17
Uname: Linux 4.10.0-32-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
CurrentDesktop: GNOME
Date: Tue Aug 15 23:05:40 2017
SourcePackage: coreutils
UpgradeStatus: No upgrade log present (probably fresh install)